Patient connectors are generally used for connecting patients to respirators, anesthesia devices, etc. When a patient is interfaced to such respirators and/or anesthesia devices, often the air that the patient breathes in is very dry and often cool. To reduce the negative effects of breathing this cool, dry air, prior patient connectors often include in-line heat and moisture exchange devices (HME devices). Heat and moisture exchange devices capture heat and moisture when the patient exhales and returns the heat and moisture to the patient when the patient inhales. As the patent exhales, the patient's breath is very humid and warm and this heat and humidity is captured in the HME and the heat and humidity is released when the patient inhales, making the air that the patient inhales warmer and more humid. Unfortunately, the actual membrane used is the heat and moisture exchange is not compatible with medicines. Typically, patients are administered medicine with the help of a nebulizer which finely divides the medicine into fine droplets which are inhaled. If a nebulizer is used in conjunction with a heat and moisture exchange device, exposure of the heat and moisture exchange element to the medication will impact the operation of the heat and moisture exchange element and possibly permanently damage the heat and moisture exchange element.
In the past, heat and moisture exchange devices had to be removed from the circuit when the patient is given medicine by way of a nebulizer. This method suffered from the complexity of rearranging the airway circuit during the administration of the medicine, then reconnecting the airway circuit and the time lag in which the circuit is disconnected.
Some circuits introduced the output of the nebulizer downstream, away from the heat and moisture exchange element as in U.S. Pat. No. 5,546,930 issued on Aug. 20, 1996. In this, a long tube separates the heat and moisture exchange element from the medicine injection point and a manually removable cap covers the port in which the nebulizer is removably attached. In this type of circuit, after the patient inhales some air mixed with nebulized medication, some amount of nebulized medication remains in the patient's airways and in the patient end of this circuit and, upon exhaling, some of this nebulized medication flows through a second leg of the circuit and into the heat and moisture exchange element, which is not desired.
Recognizing this issue, other devices have a knob, valve, or switch which initiates bypass of the heat and moisture exchange element. One such example is U.S. Pat. No. 7,594,509, issued Sep. 29, 2009. The problem with a manual function that bypasses the heat and moisture exchange element is that a busy caregiver must remember to re-enable the heat and moisture exchange element after the medication is administered, which does not always happen and, the results of such are often not readily know, so the patient starts feeling discomfort after the caregiver has left the patients proximity. Additionally, it is easy for the caregiver to forget to bypass the heat and moisture exchange element and administer the medication while the heat and moisture exchange element is in the circuit, leading to future problems with the heat and moisture exchange element and a potential reduction in the medication administered to the patient, as some of the medication becomes trapped in the heat and moisture exchange element.
What is needed is a circuit that will automatically remove the heat and moisture exchange element while the nebulizer is attached to the circuit.